Yield:66411-17-4 100%

Reaction Conditions:

with bromine;acetic acid at 25 - 80; for 16 h;

Steps:

1 Step 1 - 6,7-Dibromo-2,3-dihydro-1,4-benzodioxine-5-carboxylic acid

To a solution of 2,3-dihydro-1,4-benzodioxine-5-carboxylic acid (4.40 g, 24.4 mmol, CASNo. 4442-53-9) in AcOH (27 mL) was added Br2 (11.7 g, 73.2 mmol) dropwise at 25 °C. The mixture was stirred at 80 °C for 16 hours. On completion, the mixture was quenched with water (20 mL) and extracted with ethyl acetate (25 mL 3). The combined organic phase was washed with a solution of NaHCO3 and was dried over anhydrous sodium sulfate, filtered and concentrated to give the title compound (10.5 g, 100% yield) as a brown solid. 1H NMR (400 MHz, DMSO-d6) δ 14.43 - 12.43 (m, 1H), 7.35 (s, 1H), 4.31 - 4.28 (m, 4H).

References:

WO2021/188948,2021,A1 Location in patent:Paragraph 001916; 001917-001918